For safety of 12V LISB batteries mounted in vehicles, relays are provided. 12V LISB batteries are different from 12V lead accumulators and high voltage batteries. 12V lead accumulators have been long used for a long time and safety is guaranteed, so relays for preventing danger are absent in the battery system. In case of 12V LISB batteries, development is in progress and danger still exists, and to avoid danger, relays are provided. Additionally, 12V LISB batteries are a low voltage battery, and opposed to conventional high voltage battery, they constantly supply power to ECU after being mounted in the vehicle.
Particularly, in the case of electric vehicles, 12V LISB batteries (hereinafter referred to as “12V batteries”) must constantly supply power to the vehicles. For example, when power supply from 12V battery is stopped while driving, a dangerous situation occurs in which the vehicle stop driving and electrical operations such as handle manipulation and brake manipulation stop. When power supply from 12V battery is stopped, a phenomenon occurs in which the ECU system in the vehicle is reset. That is, even in parking state in which the ECU system is off, when power supply is stopped, the ECU system is reset and information of the vehicle (e.g., car seat position information, radio frequency information, driving distance information and information stored by a user, etc.) is deleted. Accordingly, open of the relay should take place only in an intended situation such as vehicle repair and explosion prevention of the 12V battery. That is, when a dangerous situation such as a battery explosion is sensed, open of the relay is necessarily required.
However, 12V batteries have been manufactured for the purpose of long-term use (e.g., 7 years or longer), and during the long-term use, relays of 12V batteries are maintained in closed state most of the time, and relays have hardly any chance to be controlled into open state, failing to identify if open/closed of relays normally works.